Question

Two slits separated by 0.200 mm are to be used in Young’s double – slit experiment. Immediately behind the slits in a lens of focal length 0.500 m used to form the interference pattern on a screen located in the focal plane of the lens. What is wavelength of a monochromatic light source used to illuminate the slits if adjacent maxima of the interference pattern are separated by 1.00 mm?

• A. 400 nm
• B. 500 nm
• C. 600 nm
• D. 700 nm

Answer 1

The correct option is A 400 nm

$\beta =\frac{\lambda D}{d},D=0.5m,d=0.2\times {10}^{-3}m,\beta =1\times {10}^{-3}m$
So answer is 400 nm